A material dispense tip, also referred to as a “pin” or “needle,” is utilized in a variety of applications. For example, a material dispense tip, when attached to a material dispensing pump system, is used to deposit a precise amount of fluid material, such as glue, resin, or paste, at precise positions on a semiconductor substrate. Examples of such material dispensing pumps are described in U.S. Pat. Nos. 6,511,301, RE 40,539, 6,892,959, 6,983,867, and 7,331,482, the contents of each of which are incorporated herein by reference in their entirety.
A material dispense tip can be formed according to one of several different approaches. In one approach, a dispense tip can be formed by machining a first stock to form a cylindrical neck, machining a second stock to form a cylindrical base, boring a first hole in the base, inserting the neck into the hole in the base, and forming a second hole through the base and neck.
In another approach, the neck and the base can be unitary and machined from a common stock, for example, stainless steel, or the neck and the base can be molded from ceramics.
In another approach, the neck and the base can each be formed by different methods, and of different materials. For example, the dispense tip can include a molded ceramic neck that is attached to a machined steel base.
The dispense tip can be attached to a material dispensing pump by inserting the base into a cavity in the pump. The base is held in place in the cavity, for example, by a female Luer™-style fitting, which can interface with a corresponding male Luer™-style fitting on the pump. The dispense tip can alternatively be “surface mounted” to a pump, wherein the base of the dispense tip is held in place against an outlet surface of the pump by a nut or other retaining device.
However, when conventional dispense tips are attached to a material dispensing pump, fluid material can leak from an interface between the base of the dispense tip and the pump due to the presence of imperfections such as nicks, cracks, burrs, protrusions, blemishes, dents, or other imperfections on the interfacing surface of the base or on the pump surface against which the base abuts.
Also, a high solvent content may be included in the fluid material to be dispensed in order to prevent the fluid material from coagulating, congealing, drying up and the like in the material path of the dispense tip and the pump. However, these solvents can leach from the material and escape from cracks or crevices in the interfacing surface of the dispense tip, causing the material to dry up and clog the material path. Such solvents may also permeate the feed tube of the material dispense pump or the wall of the dispense tip, depending on the material used to form the dispense tip. For example, in a case where polypropylene or silicone materials are employed to form the dispense tip, certain solvents can permeate these materials.
The base of a conventional dispense tip can be formed by machining plastics. These plastics can be highly stable, possess favorable hardness properties, be resilient to solvents, and adhere to molded necks, such as ceramic necks, using adhesives such as two-part epoxy.
In addition, the base comprising such plastics can be machined to close tolerances. However, when machining these plastics from a stock, it is difficult to deburr the finished base from the stock, which can impede the flow of material in the material path formed by holes in the base and neck, or can clog the dispense tip. Further, these plastics have high viscosity properties, which are undesirable for precision micromolding, since such plastics can be prone to imperfections when filling a mold during the molding process for forming the dispense tips.